Share this:

Sea lion pups jockey at the Marine Mammal Center in Rodeo Beach on Thursday. The clinic is treating four times the usual number of sea lions for this time of year. (Robert Tong/Marin Independent Journal)

The Marine Mammal Center near Rodeo Beach treats dehydrated and malnourished animals. One biologist said sea lion pups have been arriving at the center at unprecedented low weights. (Robert Tong/Marin Independent Journal)

When a California sea lion dubbed “School Daze” was rescued by the Marine Mammal Center after wandering onto Highway 37 last week, it underscored the plight of a species that is finding itself in trouble throughout the state.

School Daze is one of more than 80 young sea lions being treated at the mammal center, which is near Rodeo Beach in the Marin Headlands. The total is more than four times the average of what the clinic typically sees this time of year.

The influx makes it the fourth year in a row of sea lions in peril, the center says.

“The initial shock of seeing so many starving sea lions is over and now we’re really starting to worry about long-term impacts on the population as a whole,” said Dr. Shawn Johnson, director of veterinary science at the center.

Officials with the National Oceanic and Atmospheric Administration say more than 1,000 sick and starving young sea lions have washed up on California beaches so far in 2016. That compares to about 225 sea lion strandings that officials normally would see between January and April.

An estimated 300,000 sea lions live from the Mexican border to Washington state and the overall population is healthy, but it is dropping and will continue to do so as the young struggle to survive, scientists say. NOAA has declared their plight as an “unusual mortality event.”

Scientists say sea lions prey on creatures such as sardines, anchovies and squid, which thrive in cold water. But in recent years warmer coastal waters have forced prey away from nursing mothers in the Channel Islands south of Santa Barbara where sea lions are born.

As mothers struggle to find food, young pups — now about 9 months old — are not being nourished by the mothers’ milk and are dying at the rookery. Some pups leave to look for food on their own, but many do not have the life skills to catch prey on their own. Those pups bob in the water, getting hungrier and hungrier and more emaciated by the day until they come up on shore.

El Niño complication

The double whammy of an El Niño year has made the seas rougher and has further added to the problem. Throughout the mammal center’s 41-year history, it has typically seen higher numbers of marine mammal strandings during El Niño years as the ecosystem changes affect fish populations and increase stress on the animals.

Sea lions aside, the center has more than double the elephant seal pups and four times as many harbor seals than typically seen this time of year. But those populations should stabilize once El Niño is over.

But it’s a different story with the sea lions.

At the mammal center, more starving sea lions are arriving every day. As soon as a pup arrives at the center they receive a physical exam, antibiotics and deworming. They are fed up to four times a day with a fish gruel consisting of ground up herring, fish oil and water. If they can handle that, it’s on to frozen herring.

“They are skin and bones, they are malnourished, they have secondary infections like pneumonia because their immune systems are suppressed,” said Johnson as he walked near pens at the center, which are filled with yowling, wide-eyed pups. “They are desperate.”

The numbers seen at the center are actually down compared to last year, but that doesn’t mean sea lions are in better shape.

“There have been more strandings in Southern California and fewer are making it up to our range because they are so weak,” Johnson said.

NOAA scientists warn more sea lion pups might beach themselves in the coming months as they wean and venture off on their own.

Domoic acid toxicity

School Daze, the wayward and emaciated sea lion found on Highway 37, might have been affected at birth by domoic acid toxicity, the same toxin that caused the most recent Dungeness crab fishing season to be delayed. While that has been an issue for sea lions in years past, it is the ocean environment that is the biggest factor for the species’ problems.

New research indicates a decade-long trend of declining fish populations in the suddenly warmer waters near sea lion breeding areas may to blame. NOAA scientists analyzed changes in sea lion prey and found that high-calorie sardines and anchovies, both rich in fat that is vital to the growth of young sea lions, have declined in the last 10 years in the areas near the Channel Islands.

It is unclear what is causing the ocean to warm, said Sharon Melin, NOAA wildlife biologist and sea lion expert.

In addition to being dehydrated and emaciated, the sea lions appear to be experiencing stunted growth. Nine-month-old pups are arriving at the mammal center at little more than birth weight of 14 pounds, center officials said.

“These are the smallest pups we have seen in 41 years of study,” Melin said.

If there is any good news, it’s that sea lions are resilient in the right conditions. The population dipped as low as 11,000 but the Marine Mammal Protection Act of 1972 helped stave off the decline and boost numbers.